This metal has been known since prehistoric times
Gold is a soft metal with a characteristic yellow colour. It is the most malleable and ductile of any element. It is unaffected by air, water, alkalis and acids, with the exception of “aqua regia”, a mixture of concentrated nitric and hydrochloric acids, usually one part of the former to three parts of the latter by volume. This mixture was given its name , that means “royal water” because of its ability to dissolve gold and other noble metals.
The fact that it is chemically unreactive, means that it is often found in its natural state. It is a good thermal and electrical conductor and has excellent reflective properties to both light and infrared. Most of the metal found in the Earth is retained for use as bullion reserves, but some is used within the electronics and jewellery industries, where it is frequently alloyed with other elements to improve the mechanical properties of the metal (e.g. copper and silver). Other uses for the metal are as a heat reflecting coating for glass as well as a decorative medium.
The most important industrial use of gold is in the manufacture of electronics. Solid state electronic devices use very low voltages and currents which are easily interrupted by corrosion or tarnish at the contact points. Gold is the highly efficient conductor that can carry these tiny currents and remain free of corrosion. Electronic components made with gold are highly reliable. Gold is used in connectors, switch and relay contacts, soldered joints, connecting wires and connection strips.
A small amount of gold is used in almost every sophisticated electronic device. This includes cell phones, calculators, personal digital assistants, GPS units, and other small electronic devices. One challenge with the use of gold in very small quantities in very small devices is loss of the metal from society. Nearly one billion cell phones are produced each year, and most of them contain about fifty cents worth of gold, and very few are currently recycled. Although the amount of gold is small in each device, their enormous numbers translate into a lot of unrecycled gold.
Gold is used in many places in the standard desktop or laptop computer. The rapid and accurate transmission of digital information through the computer and from one component to another requires an efficient and reliable conductor. Gold meets these requirements better than any other metal. The importance of high quality and reliable performance justifies the high cost.
Edge connectors used to mount microprocessor and memory chips onto the motherboard and the plug-and-socket connectors used to attach cables all contain gold. The gold in these components is generally electroplated onto other metals and alloyed with small amounts of nickel or cobalt to increase the durability.
Gold has many uses in the production of glass. The most basic use in glassmaking is that of a pigment. A small amount of gold, if suspended in the glass when it is annealed, will produce a rich ruby colour.